Cartesian product and symmetric difference

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SUMMARY

The discussion centers on proving the equality \( A \times (B \Delta C) = (A \times B) \Delta (A \times C) \) for three sets A, B, and C. Participants explore the proof by analyzing elements of the Cartesian products and symmetric differences. The proof is established by demonstrating that an arbitrary element \( p \) in \( A \times (B \Delta C) \) can be shown to belong to \( (A \times B) \Delta (A \times C) \) and vice versa, confirming the equality.

PREREQUISITES
  • Understanding of set theory concepts, specifically Cartesian products and symmetric differences.
  • Familiarity with notation for set operations, including \( \Delta \) for symmetric difference and \( \times \) for Cartesian products.
  • Basic proof techniques in mathematics, particularly element-chasing arguments.
  • Knowledge of set operations such as union, intersection, and set difference.
NEXT STEPS
  • Study the properties of symmetric differences in set theory.
  • Learn about Cartesian products and their applications in mathematics.
  • Explore formal proof techniques, focusing on element-based proofs in set theory.
  • Investigate related set identities and their proofs for deeper understanding.
USEFUL FOR

Mathematicians, students of discrete mathematics, and anyone interested in set theory and formal proofs will benefit from this discussion.

fatineouahbi
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Let A,B,C be three sets . Prove Ax(BΔC)= (AxB) Δ (AxC)

I tried to start with this :

Let p be an arbitrary element of Ax(BΔC)
then p=(x,y) such that x ∈ A and y ∈ (BΔC)
x ∈ A and (y∈ B\C or y∈ C\B)
(x ∈ A and y ∈ B\C) or (x ∈ A and y ∈ C\B)

But I don't know how to continue or if I should even start with this .
 
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fatineouahbi said:
Let A,B,C be three sets . Prove Ax(BΔC)= (AxB) Δ (AxC)

I tried to start with this :

Let p be an arbitrary element of Ax(BΔC)
then p=(x,y) such that x ∈ A and y ∈ (BΔC)
x ∈ A and (y∈ B\C or y∈ C\B)
(x ∈ A and y ∈ B\C) or (x ∈ A and y ∈ C\B)

But I don't know how to continue or if I should even start with this .

It is right so far.When does it hold that $p \in (A \times B) \triangle (A \times C)$ ?
 
evinda said:
It is right so far.When does it hold that $p \in (A \times B) \triangle (A \times C)$ ?

Hello :) Thank you , I think I may get it now ?

(x ∈ A and y ∈ B\C) or (x ∈ A and y ∈ C\B)
then p ∈ Ax(B\C) or p ∈ Ax(C\B)
then p ∈ (AxB) \ (AxC) or p ∈ (AxC) \ (AxB)
thus p ∈ (AxB) △ (AxC)
then Ax(BΔC) ‎⊂ (AxB) Δ (AxC)

Then I'll just try to go backwards maybe ?
 
fatineouahbi said:
Hello :) Thank you , I think I may get it now ?

(x ∈ A and y ∈ B\C) or (x ∈ A and y ∈ C\B)
then p ∈ Ax(B\C) or p ∈ Ax(C\B)
then p ∈ (AxB) \ (AxC) or p ∈ (AxC) \ (AxB)
thus p ∈ (AxB) △ (AxC)
then Ax(BΔC) ‎⊂ (AxB) Δ (AxC)
Well done, you are right :)

fatineouahbi said:
Then I'll just try to go backwards maybe ?
Yes, you pick an element in $(A \times B)\triangle (A \times C)$ and you need to show that it is also in $A \times (B \triangle C)$.
 
evinda said:
Well done, you are right :)

Yes, you pick an element in $(A \times B)\triangle (A \times C)$ and you need to show that it is also in $A \times (B \triangle C)$.

Thank you so much !
 

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